本研究以CFD商業軟體FLUENT進行數值模擬，研究以奈米非牛頓流體作為交叉橢圓管套管內管部分的工作流體時，所發生的熱交換行為。故此，文中探討的面相共三部分，包含：流動特性指數(n)、內管和外管入口初速、奈米體積分率(φ)。接著對下列幾方面進行溫度場與流場的分析，分別是：在選定管道位置的溫度場和流線截面圖、平均紐賽數(Nu)、相對於水的傳熱增強因子(η)、內管道局部紐賽數、內管道局部熵增(S'gen)、選定管道位置的場協同角分布、壓降(ΔP)。計算結果顯示，降低流動特性指數可以有效降低流體因為加入奈米粒子而提高的壓降，同時保留熱傳效果提升的優點。其次，增加內管與外管的入口初速皆有助於熱傳效果的提升，然而提高內管入口初速，相較提高外管入口初速更能強化熱傳效果。最後，奈米體積分率的提高亦能幫助熱傳效果變好，但隨著奈米體積分率上升，流動特性指數能減少的壓降比例會逐漸降低。

In this study, computational fluid dynamics (CFD) commercial package software have been used on numerical simulation. The heat exchange behavior of nano-non-Newtonian fluid, which flows in the inner tube of a double pipe with staggered oval inner sections is investigated. Therefore, the aspect of investigation can divide into three parts, including flow behavior index (n), inlet velocity of inner or outer tube and volume fraction of nanoparticles (φ). Then, temperature and flow field analysis have been conducted. The results include temperature contours, streamlines and synergy angle contour at selected cross section (L=373 mm), average Nusselt number (Nu), heat transfer enhancement factor (η) versus water, pressure drop (ΔP), local Nusselt number and local entropy generation (S'gen) of inner tube. First, the computation shows that reducing the flow behavior index of working fluid not only can effectively lessening the pressure drop as adding nanoparticles, but also preserve the advantage of improving heat transfer effect. Second, increasing inlet velocity of inner or outer tube both help enhance the effect of heat transfer. Besides, comparing with outer tube, it has more effect on arising inlet velocity of inner tube. Last, increasing nanoparticle volume fraction also help improve the effect of heat transfer. However, the more volume fraction increases, the less percentage of pressure drop reducing by flow behavior index decrease.

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